Patient self-inflicted lung injury and positive end-expiratory pressure for safe spontaneous breathing

Abstract

Purpose of review The potential risks of spontaneous effort and their prevention during mechanical ventilation is an important concept for clinicians and patients. The effort-dependent lung injury has been termed ‘patient self-inflicted lung injury (P-SILI)’ in 2017. As one of the potential strategies to render spontaneous effort less injurious in severe acute respiratory distress syndrome (ARDS), the role of positive end-expiratory pressure (PEEP) is now discussed. Recent findings Experimental and clinical data indicate that vigorous spontaneous effort may worsen lung injury, whereas, at the same time, the intensity of spontaneous effort seems difficult to control when lung injury is severe. Experimental studies found that higher PEEP strategy can be effective to reduce lung injury from spontaneous effort while maintaining some muscle activity. The recent clinical trial to reevaluate systemic early neuromuscular blockade in moderate–severe ARDS (i.e., reevaluation of systemic early neuromuscular blockade (ROSE) trial) support that a higher PEEP strategy can facilitate ‘safe’ spontaneous breathing under the light sedation targets (i.e., no increase in barotrauma nor 90 days mortality versus early muscle paralysis). Summary To prevent P-SILI in ARDS, it seems feasible to facilitate ‘safe’ spontaneous breathing in patients using a higher PEEP strategy in severe ARDS.

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“…The level of specific stress-strain associated with the initiation of VALI P TP : transpulmonary pressure, V T : tidal volume, P: pressure, V: volume, F: force, A: area, L: length, RR: respiratory rate, VALI: ventilator-associated lung injury. and clinical studies have shown that excessively vigorous spontaneous efforts can lead to aggravation of VALI [28][29][30][31]. The risk of a condition coined as P-SILI or effort-induced lung injury is strongly associated with moderate-to-severe ARDS.…”

“…A too vigorous respiratory drive due to patient respiratory efforts and excessive P TP will result in global and local overdistension of lung tissue [30,33]. Thus, there are three primary mechanisms associated with P-SILI: pulmonary overdistension, increased lung blood flow, and patient ventilator asynchrony (double and reverse triggering) [31].…”

“…In summary, a high PEEP level (10-24 cmH 2 O; Table 2) should be considered only for patients with moderate-to-severe ARDS with low risk of arrhythmias and barotrauma in parallel with thor-ough hemodynamic and respiratory monitoring. Increased PEEP can also be useful to reduce the risk of P-SILI and avoid the need for neuromuscular blockade [27,31]. The increase in PEEP should be titrated and gradual (by 2 cmH 2 O per several minutes) and should not result in V T exceeding 8 ml/kg, P PLAT above 30 cmH 2 O, and P DRIVE above 15 cmH 2 O [1,47].…”

“…Attempts to reduce respiratory rate and V T result in a decrease in minute volume and damaging power; however, they can be associated with permissive hypercapnia (PaCO 2 45-70 mmHg). The damaging effects of excessive spontaneous efforts to breathe can be suppressed by deep sedation and/ or neuromuscular blockade and high PEEP to decrease swings in PTP, the work of spontaneous breathing, the response to permissive hypercapnia, and, finally, the risk of P-SILI [26,31]. All determinants of power and energy should be optimized, including gradual changes in PEEP (controlled to produce specific P DRIVE and V T ), minute ventilation, respiratory rate, flow magnitude and profile, and the I : E ratio.…”

“…Therefore, in this subset of ICU patients, low V T is prudent, safe, and is associated with better outcomes [73,74]. Furthermore, use of a high PEEP level is more controversial and should perhaps be used only in situations where the risk of P-SILI exists, when it can decrease V T to normal values and attenuate static strain injury [15,30,31].…”